CA1180342A

CA1180342A - Process for synthesising allyl carbonates of polyhydric alcohols and their dervatives

Info

Publication number: CA1180342A
Application number: CA000372281A
Authority: CA
Inventors: Ugo Romano; Giuseppe Iori
Original assignee: Anic SpA
Current assignee: Anic SpA
Priority date: 1980-03-05
Filing date: 1981-03-04
Publication date: 1985-01-02
Also published as: US4623705A; NO154129B; US4508656A; IE810365L; EP0035304B2; ES8201942A1; JPS56133246A; DK186291A; DE3162072D1; DK163236C; NO154128B; NO810711L; DD157795A5; DK171867B1; NO814269L; CS219853B2; DK84781A; DK163236B; EP0035304B1; ES500632A0

Abstract

PROCESS FOR SYNTHESISING ALLYL CARBONATES OF POLYHYDRIC
ALCOHOLS AND THEIR DERIVATIVES

ABSTRACT OF THE DISCLOSURE:

The application relates to a process for synthesising carbonic allyl esters from polyhydric alcohols, which are reacted with diallyl carbonate in the presence of a basic catalyst, which can be chosen from sodium hydroxide, sodium carbonate, sodium alcoholate, organic bases or basic ion exchange resins. The final products obtained differ according to the ratio of the components of the starting mixture. Thus, in the case of diols with a diallyl carbonate/diol ratio great-er than or equal to 10, the resultant product is constituted by the bis allyl carbonate of the diol together with a quantity of less than or equal to 10% of oligomers repre-sented mainly by dimers. If the ratio is less than 10, the percentage of oligomers rises until, in the case of an approximately stoichiometric ratio, it reaches a value close to 70% of the reaction product.

Description

PROCESS FOR SYNTHESISING ALLYL CARBONATES OF POLYHYDRIC
ALCOHOLS AND THEIR DERIVATIVES
This invention relates to a process ~or synthesising carbonic allyl esters of formula CH2 = CH - CH2 OCOOROCOOCH~ - CH = CH2 particularly starting from polyhydric alcohols, which consists of reacting diallyl carbonate with the alcohol concerned in the presence of a basic catalyst. The product or monomer component thus obtained may then be used in post-modification or polymerisation reactions to prepare valuable derivatives of varied use, these derivatives constituting an integral part of the present invention. It is well known that bis allyl carbonates of glycols and/or poly~lycols are commonly prepared by reacting allyl chloroformate with the glycol, or alterna-tively the glycol-bis-chloroformate with the allyl alcohol, the reaction always taking place in the presence of an acceptor for the hydrochloric acid which is released, as described for example in the US patents 2370565 and 2592058.
The reactions stated are such that the products obtained are frequently coloured when in the crude state, and are thus unsuitable for immediate use in that which is considered one of the main fields of application of these compounds, namely raw materials for forming organic glass substitutes for optical purposes. The purification comprises stages such as decoloration and/or distillation under reduced pressure, which considerably affect the economics of the process and a priori cannot ensure the subsequent good quality of the product.
In this respect, the presence of chloroformate among the starting materials leads to a constant presence of chlo-rinated impurities in the final products even after purifica-tion, and these impurities characterise the specific proper-ties of the product, so as to make the subsequent treatment 3~

which precedes their practical use sometimes problematic.
As stated, the present invention relates to an improved process for synthesising allyl carbonates of poly-hydric alcohols, mainly ylycols, which enables the final products to be obtained without any of the aforesaid draw-backs. The process, in general, comprises reacting together the starting substrates (polyols and allyl carbonate) at a temperature of between 50 and 150C. The starting compounds are brought into contact in the presence o~ a suitable basic catalyst, which is introduced in a quantity of at least 0.1 ppm with respect to the alcohol. The molar ratio of the diallyl carbonate to the alcohol can vary between 2 and 20.
The present invention, in particular, provides a process for the preparation of a monomer component by a transesterification reaction, said monomer component compris~
ing a mixture of diallyl carbonates of a diol or a triol and being suitahle for the preparation of organic optical glass, characterized in that diallyl carbonate is reacted with a diol, or a triol, respectively, at a temperature of from 50C to 150C and in the presence of a suitable basic catalyst, the molar ratio of the diallyl carbonate to the diol, or the triol, concerned being in the range from 2:1 to 20:1, and said catalyst being present in an amount of at least 0.1 ppm (part per million) relative to the diol, or triol, concerned, on a weight basis.
In accordance with the present invention, the reac-tion for the preparation of the monomer component may be carried out in the presence of an amount of the catalyst variable between 1 ppm and 1% by weight with respect to the diol or triol. The reaction may be carried out at a pressure of between 10 mm Hg and atmospheric pressure.
The polyhydric alcohols used (i.e. the diol or triol) ,~, 3~L~
- 2a -can be chosen from a wide range, for example eth~lene glycol, propylene glycol, diethylene glycol, triethylene gl~col, tetraethylene glycol, butanediol, hexanediol, glycerol etc.
The catalyst itself can be chosen from NaOH, Na2CO3, sodium alcoholate, organic bases or basic ion exchange resins.
In accordance with the present invention, there is particularly provided a process for the preparation of a monomer component by a transesterification reaction, said monomer component comprising a mixture of diallyl carbonates of a diol and being suitable ~or the preparation of organic optical glass, characterized in that diallyl carbonate is reacted wi~h a diol, at a temperature of from 50~C to 150C
and in the presence of a suitable basic catalyst, the molar ratio of the diallyl carbonate to the diol being in the range from 2:1 to 20:1, said catalyst being present in an amount of at least 0.1 ppm (part per million) relative to the diol on a weight basis. The diol may be a member selected from the group consisting of diethylene glycol, triethylene glycol and tetraethylene glycol.
In accordance with the present invention, the molar ratio of the dialkyl carbonate to the diol may be in the range of from 10:1 to 20:1.
The reaction can be carried out using commercially available products as the starting substances without further purification.
The final products are absolutely colourless and free from those impurities which, as stated, lead to the disadvantages of the products obtained according to the known art.
With the present method of synthesis, a mixture of ester with oligomers constituted by chains of allyl terminated alcohol polycarbonate may be obtained, 8~33g.2 according to the diallyl carbonate/polyhydric alcohol molar ratio. The structure of the monomer and oligomers in the case of glycol is as follows:

C~2=CH-CH2-OCO~ROCO)nCH2-CH=CH2 O O
where n lies between 1 and 10, and R represents a hydrocarbon radical.
If the diallyl carbonate/glycol ratio is greater than or equal to 10, the final product is formed by the allyl carbonate of the glycol with a quantity of less than or equal to 10% of oligomers mainly represented by dimers (n=2). If the ratio is less than 10, the oligomer percentage rises until, for an approximately stoichiometric ratio, it reaches a value close to 70~ of the reaction product.
The density and viscosity of the product increase in relation to the increase in oligomer concentration.
By way of example, some characteristics of the product obtained from diallyl carbonate (DAC) and diethylene glycol (DEG) for various molar ratios are as follows:
Mol ratio. % mon. % olig. Density Viscos. cst DAC/DEG (25C) 12 94 6 1.148 12 8 81 19 1.151 17 3.5 52 48 - 32

2.5 40 60 - 64 The Saybolt colour is constantly greater than ~30, and the W -visible absorbency is as follows:

nM 300 350 400 450 600 700 ~bsorbency Q.2 0.04 0 0 0 0

3~2 The only volatile impurities (BP < 150 at 5 mmHg) which can be present are traces of diallyl carbonate ( < 1%).
According to one embodiment of the process of the invention, the reaction between diallyl carbonate and the polyhydric alcohol is carried out in a vessel fitted with a stirrer and distillation column for removing the allyl alcohol released by the transesterification reaction.
The carbonate and alcohol are thus fed in the required molar ratio, and the environment is deaerated before introducing the catalyst. With diethylene glycol, for example, the catalyst is added in dispersed solid form or in preferably alcoholic solution to the extent of 0.5 to 10 ppm by weight of Na with respect to the diethylene glycol used.
Heating is then started under a residual pressure of 150-200 mmHg, taking particular care to have no infiltration of air. The allyl alcohol, which is released to the extent of 2 moles per mole of fed glycol, rapidly distils over, and the reaction is terminated in about 1 hour. The residual vacuum is then gradually increased to remove the excess of diallyl carbonate. The diallyl carbonate which remains in the product is a function of the degree of vacuum at which this removal is carried out. In particular, if operating at 10 mmHg, the diallyl carbonate remaining in the product is less than 1~.
The residual product, after filtering and possibly washing with water and dehydrated, is perfectly clear, colour-less and suitable for the application for which it is intended.
The esters thus obtained can for example be directly used in radical polymerisation reactions in bul~, to give products of high technological value.

In the particular case of polymerisation, this may be carried out in the presence of initiators or free radicals of . ~

a ~ A ~r~
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peroxide or peroxycarbonate type in a percentage variable between 1 and 12~ with respect to the monomer~ at a tempera-ture of between 30 and l~O~C.
Thus, in accordance with another aspect, the present invention provides a process for preparing polymers from a monomer component comprising a mixture of diallyl carbonates of a diol or a triol, suitable for the preparation of organic optical glass, said mixture having been prepared as refered to above, characterized in that the polymerization reaction is carried out in the presence of a radical initiator which is a member selected from the group consisting of peroxides and peroxycarbonates, the quantity of said radical initiator relative to the monomer concerned being in the range from 1%
to 12% on a weight basis, said polymerization reaction being carried out at a temperature of from 30C to 120C.
The polymerization may be carried out for a time variable from a few hours to several hours.
In accordance with the present invention, the polymerization may be carried out at a temperature of from 40C to 90C for a time between 2 and 24 hours.
In accordance with the present invention, polymers may be prepared which have a transmission coefficient of light radiations visible to the human eye of above 89% when measured on a thickness of 2.7 m at 350-700 nanometer wave-length.
Thus, for example, the present invention provides a process for preparing polymers having a transmission coeffi-cient of the light radiations visible to the human eye of above 89% when measured on a thickness of 2.7 m at 350-700 r.anometer wavelenght, characterized in that a monomer compo-nent is subjected to a polymerization reaction which is carried out in the presence of a radical initiator which is a ~ ,, 33~
- Sa -member selected from the group consisting of peroxides and peroxycarbonates, the quantity o~ said radical initiator relative to the monomer component concerned being in the range from 1% to 12~ on a weight basis~ said polymerization reaction being carried out at a temperature of from 30C to 120C, said monomer component comprising a mixture of diallyl carbonates of a diol, suitable for the preparation of organic optical glass, said mixture having been obtained by a transesterifica-tion reaction wherein diallyl carbonate is reacted with a diol, at a temperature of from 50C to 150C and in the presence of a suitable basic catalyst, the molar ratio of the diallyl carbonate to the diol being in the range from 2:1 to 20:1, said catalyst being present in an amount of at least 0.1 ppm (part per million) relative to the diol on a weight basis.
The diol may be a member selected from the group consisting of diethylene glycol, triethylene glycol and tetraethylene glycol.
The moulds of the required shape, which are usually of carefully machined glass or steel fitted with an elastic gasket in order to follow the volume contraction of the product under polymerisation, are completely filled with the monomer to which the filtered and desaerated catalyst is added.
They are then placed in an air or water oven and left there to polymerise for a time and temperature cycle which vary with the dimensions of the mould, the thickness, the type and percentage of catalyst.
Generally, an increasing temperature of between 40 and 100C is maintained for a time varying from a few hours to several tens of hours.

At the end of the determined cycle, the product, which is now at the termination of cross-linkage, can be released from the mould and subjected to fin~l hardening by - 5b -heat treatment in air ovens at a temperature of about90-llO~C for a time of between 1 houx and a f~w hours. The products thus treated attain a very high and constant quality standard.
The measurement of the chemical and physical characteristics of the various products demonstrates a complete and,properly conducted polymerisation cycle.
Using the described polymerisation method, test pieces uniform in terms of shape and dimensions were obtained, and these were then subjected to measurements of optical-mechanical properties significant for the main use for which these polymers are intended, i.e. as glass substitutes.
The polymerisation for example of the various samples of carbonic allyl esters of diethylene glycol always /

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followed the scheduled temperature and duration cycles, and never gave rise to any difficulties during cross-linkage, or on opening the moulds, such as breakages or separation difficulties.
The transmission values for light from 350 to 700 nM
are constantly above 89%.
The Rockwell hardness measured on test pieces deriving from distilled ester is maintained at around values of M 100, while falling to values of M 85 for test pieces originating from ester containing 70~ of monomer and 30% of oligomer carbonates, and reducing to values of M 50 for test pieces originating from ester in which the oligomer carbonates represent 60% of the product.
The resistance to scratching is high for all samples, and this appears substantially independent of the percentage of oligomers in the initial allyl carbonate ester.
However, the impact resistance increases considerably with this percentage. The bending modulus is also constant within certain limits, and is reduced for test pieces originating from esters containing 60% of oligomers.

12 moles of diallyl carbonate and 1 mole of diethylene glycol are mixed at ambient temperature under an inert atmosphere in a 3 neck flask fitted with a thermometer, stirrer and distillation column. When mixing is complete, 0.05 milli-moles of powdered NaOH are added, and heating is commenced at a residual pressure of 150 mmHg.
After the two moles of released allyl alcohol have been withdrawn as overheads, the residual pressure is lowered to 2 mmHg in order to remove the excess diallyl carbonate.
perfectly colourless product (Saybolt colour > +30) is obtained on the bottom, and is composed of ~8V~

Diallyl carbonate 0.5% by weight Diethylene ~lycol bis allyl carbonate 89.85~ by weight Oligomers 9.65% by weight This product is washed with water until neutral, dried and filteredO The yield with respect to the fed diethylene glycol is total.

The reaction is carried out as in example 1, with the difference that 0.005 millimoles of sodium methylate are used as catalyst. The sodium methylate was introduced as a 30~ methanol solution, again under an inert atmosphere.
When the reaction was finished, the colourless bottom liquid was washed, dried and filtered.
The yield is total with respect to the fed diethylene glycol.
The composition of the product is:
Diallyl carbonate 0.5 Diethylene glycol bis allyl carbonate 91.5 Oligomers 300 The reaction is carried out as in example 2, the only difference being that the catalyst was introduced as a solid, and after removing the excess of diallyl carbonate the perfectly colourless bottom product is only filtered. Yield and composition as in example 2.

The reaction is carried out as in example 2, except that the diallyl carbonate:diethylene glycol molar ratio was 10:1. The perfectly colourless bottom product is washed, dehydrated, filtered and analysed. The yield with respect to the fed diethylene glycol is total. The composition is as follows:

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Diallyl carbonate 0.5 Diethylene glycol bis allyl carbonate 85.3 Oligomers 14.2 Viscosity at 25~ 15.15 cst The reaction described in example 4 is carried out at the followin~ diallyl carbonate/diethylene glycol ratios.
Example Diallyl Composition Viscosity Carbonate/ Monomer Oligomers cst at 25C
diethylene glycol ratio 8:1 81 19 0.17 6 5:1 60 40 19 73.5:1 52 48 32 82.5:1 40 60 64 The reaction is carried out as in example 2, the only difference being that 0.01 millimoles of metal sodium per mole of diethylene glycol are used as catalyst.
After the excess diallyl carbonate has been removed, a slightly yellow bottom product of identical composition to the product of test 2 remains.
Purification is carried out by distilling at a residual pressure of 2 mmHg and a temperature of 160C.
Perfectly colourless diethylene glycol bis allyl carbonate is obtained, with a yield of 80~ with respect to the fed diethylene glycol.
A very viscous yellow product remains in the bottom, consisting mainly of allyl terminated oligomer carbonates.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for preparing polymers having a transmission coefficient of the light radiations visible to the human eye of above 89% when measured on a thickness of 2.7 m at 350-700 nanometer wavelength, characterized in that a monomer component is subjected to a polymerization reaction which is carried out in the presence of a radical initiator which is a member selected from the group consisting of peroxides and peroxycarbonates, the quantity of said radical initiator relative to the monomer component concerned being in the range from 1% to 12% on a weight basis, said polyme-rization reaction being carried out at a temperature of from 30°C to 120°C, said monomer component comprising a mixture of diallyl carbonates of a diol, suitable for the prepara-tion of organic optical glass, said mixture having been obtained by a transesterification reaction wherein diallyl carbonate is reacted with a diol, at a temperature of from 50°C to 150°C
and in the presence of a suitable basic catalyst, the molar ratio of the diallyl carbonate to the diol being in the range from 2:1 to 20:1, said catalyst being present in an amount of at least 0.1 ppm (part per million) relative to the diol on a weight basis and said diol being a member selected from the group consisting of diethylene glycol, triethylene glycol and tetraethylene glycol.

2. A process as defined in claim 1, characterized in that the polymerization reaction is carried out in the presence of a radical initiator which is a member selected from the group consisting of peroxides and poroxycarbonates, the quantity of said radical initiator relative to the monomer concerned being in the range from 1% to 12% on a weight basis, said polymerization reaction being carried out at a temperature of from 40°C to 90°C for a time between 2 and 24 hours.

3. A process as defined in claim 1 wherein the transesterification is carried out in the presence of an amount of said catalyst variable between 1 ppm and 1% by weight with respect to the diol.

4. A process as defined in claim 3 , wherein the transesterification reaction is carried out at a pressure of between 10mmHg and atmospheric pressure.

5. A process as defined in claim 4, wherein the transesterification reaction is carried out in the presence of a basic catalyst chosen from the group consisting of sodium hydroxide, sodium carbonate, sodium alcoholate, an organic base and a basic ion exchange resin.

6. A process as defined in claim 5 wherein for the transesterification reaction the molar ratio of the diallyl carbonate to the diol is in the range of from 10:1 to 20:1.

7. A process for preparing polymers , having a transmission coefficient of the light radiations visible to the human eye of above 89% when measured on a thickness of 2.7 m at 350-700 nanometer wavelength, characterized in that a monomer component is subjected to a polymerization reaction which is carried out in the presence of a radical initiator which is a member selected from the group consisting of peroxides and peroxycarbonates, the quantity of said radical initiator relative to the monomer component concerned being in the range from 1%
to 12% on a weight basis, said polymerization reaction being carried out at a temperature of from 30°C to 120°C, said monomer component comprising a mixture of diallyl carbonates of a diol, suitable for the preparation of organic optical glass, said mixture having been obtained by a transesterification reaction wherein diallyl carbonate is reacted with a diol, at a temperature of from 50°C to 150°C and in the presence of a suitable basic catalyst, the molar ratio of the diallyl carbonate to the diol, being in the range from 2:1 to 20:1, and said catalyst being present in an amount of at least 0.1 ppm (part per million) relative to the diol, on a weight basis.

8. A process as defined in claim 7, characterized in that the polymerization reaction is carried out in the pre-sence of a radical initiator which is a member selected from the group consisting of peroxides and peroxycarbonates, the quantity of said radical initiator relative to the monomer concerned being in the range from 1% to 12% on a weight basis, said poly-merization reaction being carried out at a temperature of from 40°C to 90°C, for a time between 2 and 24 hours.

9. A process as defined in claim 7 wherein the transesterification reaction is carried out in the presence of an amount of said catalyst variable between 1 ppm and 1%
by weight with respect to the diol .

10. A process as defined in claim 9, wherein the transesterification reaction is carried out at a pressure of between 10mmHg and atmospheric pressure.

11. A process as defined in claim 10, wherein the transesterification reaction is carried out in the presence of a basic catalyst chosen from the group consisting of sodium hydroxide, sodium carbonate, sodium alcoholate, an organic base and a basic ion exchange resin.

12. A process as defined in claim 11 wherein for the transesterification reaction, the molar ratio of the diallyl carbonate to the diol is in the range of from 10:1 to 20:1.

13. A process for preparing polymers having a transmission coefficient of the light radiations visible to the human eye of above 89% when measured on a thickness of 2.7 m at 350-700 nanometer wavelength, characterized in that a monomer component is subjected to a polymerization reaction which is carried out in the presence of a radical initiator which is a member selected from the group consisting of peroxides and peroxycarbonates, the quantity of said radical initiator relative to the monomer concerned being in the range from 1% to 12% on a weight basis, said polymerization reaction being carried out at a temperature of from 30°C to 120°C, said monomer component comprising a mixture of diallyl carbonates of a diol or a triol, suitable for the preparation of organic optical glass, said mixture having been obtained by a transeste-rification reaction wherein diallyl carbonate is reacted with a diol or a triol, at a temperature of from 50°C to 150°C and in the presence of a suitable basic catalyst, the molar ratio of the diallyl carbonate to the diol or triol, being in the range from 2:1 to 20:1, and said catalyst being present in an amount of at least 0.1 ppm (part per million) relative to the diol or triol, on a weight basis.

14. A process as defined in claim 13 wherein the transesterification reaction is carried out in the presence of an amount of said catalyst variable between 1 ppm and 1% by weight with respect to the diol and triol.

15. A process as defined in claim 13 wherein the transesterification is carried out at a pressure of between 10mmHg and atmospheric pressure.

16. A process as defined in claim 13 wherein the transesterification reaction is carried out in the presence of a basic catalyst chosen from the group consisting of sodium hydroxide, sodium carbonate, sodium alcoholate, an organic base and a basic ion exchange resin.

17. A process as defined in claim 13 wherein for the transesterification reaction the diol or thiol is a member selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, butanediol, hexanediol and glycerol.

18. Process for the preparation of a monomer com-ponent by a transesterification reaction, said monomer compo-nent comprising a mixture of diallyl carbonates of a diol and being suitable for the preparation of organic optical glass, characterized in that diallyl carbonate is reacted with a diol, at a temperature of from 50°C to 150°C and in the presence of a suitable basic catalyst, the molar ratio of the diallyl carbonate to the diol being in the range from 2:1 to 20:1, said catalyst being present in an amount of at least 0.1 ppm (part per million) relative to the diol on a weight basis and said diol being a member selected from the group consisting of diethylene glycol, triethylene glycol and tetraethylene glycol.

19. A process as defined in claim 18 wherein the reaction is carried out in the presence of an amount of said catalyst variable between 1 ppm and 1% by weight with respect to the diol.

20. A process as defined in claim 19, wherein the reaction is carried out at a pressure of between 10mmHg and atmospheric pressure.

21. A process as defined in claim 20, wherein the reaction is carried out in the presence of a basic catalyst chosen from the group consisting of sodium hydroxide, sodium carbonate, sodium alcoholate, an organic base and a basic ion exchange resin.

22. A process as defined in claim 21 wherein the molar ratio of the diallyl carbonate to the diol is in the range of from 10:1 to 20:1.

23. A process for preparing polymers from a monomer component comprising a mixture of diallyl carbonates of a diol, suitable for the preparation of organic optical glass, said mixture having been prepared according to the process of claim 18, characterized in that the polymerization reaction is carried out in the presence of a radical initiator which is a member selected from the group consisting of peroxides and peroxycarbonates, the quantity of said radical initiator relative to the monomer component concerned being in the range from 1% to 12% on a weight basis, said polymerization reaction being carried out at a temperature of from 30°C to 120°C.

24. A process as defined in claim 23, characterized in that the polymerization reaction is carried out in the presence of a radical initiator which is a member selected from the group consisting of peroxides and peroxycarbonates, the quantity of said radical initiator relative to the monomer concerned being in the range from 1% to 12% on a weight basis, said polymerization reaction being carried out at a tempera-ture of from 40°C to 90°C, for a time between 2 and 24 hours.

25. Process for the preparation of a monomer component by a transesterification reaction , said monomer component comprising a mixture of diallyl carbonates of a diol and being suitable for the preparation of organic optical glass, characterized in that diallyl carbonate is reacted with a diol, at a temperature of from 50°C to 150°C and in the presence of a suitable basic catalyst, the molar ratio of the diallyl carbonate to the diol , being in the range from 2:1 to 20:1, and said catalyst being present in an amount of at least 0.1 ppm (part per million) relative to the diol on a weight basis.

26. A process as defined in claim 25, wherein the reaction is carried out in the presence of an amount of said catalyst variable between 1 ppm and 1% by weight with respect to the diol.

27. A process as defined in claim 25, wherein the reaction is carried out at a pressure of between 10mmHg and atmospheric pressure.

28. A process as claimed in claim 25, wherein the reaction is carried out in the presence of a basic catalyst chosen from the group consisting of sodium hydroxide, sodium carbonate, sodium alcoholate, an organic base and a basic ion exchange resin.

29. A process as claimed in claim 25 wherein the diol is a member selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, butanediol and hexanediol.

30. A process for preparing polymers from a monomer component comprising a mixture of diallyl carbonates of a diol, suitable for the preparation or organic optical glass, said mixture having been prepared according to the process of claim 25, characterized in that the polymerization reaction is carried out in the presence of a radical initiator which is a member selected from the group consisting of peroxides and peroxycarbonates, the quantity of said radical initiator rela-tive to the monomer component concerned being in the range from 1% to 12% on a weight basis, said polymerization reaction being carried out at a temperature of from 30°C to 120°C.

31. Process for the preparation of a monomer compo-nent by a transesterification reaction, said monomer component comprising a mixture of diallyl carbonates of a diol or a triol and being suitable for the preparation of organic optical glass, characterized in that diallyl carbonate is reacted with a diol, or a triol, respectively, at a temperature of from 50°C to 150°C
and in the presence of a suitable basic catalyst, the molar ratio of the diallyl carbonate to the diol, or the triol, concerned being in the range from 2:1 to 20:1, and said catalyst being present in an amount of at least 0.1 ppm (part per million) relative to the diol, or triol, concerned, on a weight basis.

32. A process as claimed in claim 31 wherein the reaction is carried out in the presence of an amount of said catalyst variable between 1 ppm and 1% by weight with respect to the diol and triol.

33. A process as claimed in claim 31 wherein the reaction is carried out at a pressure of between 10mmHg and atmospheric pressure.

34. A process as claimed in claim 31 wherein the reaction is carried out in the presence of a basic catalyst chosen from the group consisting of sodium hydroxide, sodium carbonate, sodium alcoholate, an organic base and a basic ion exchange resin.

35. A process as claimed in claim 31 wherein the diol or triol is a member selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, triethy-lene glycol, tetraethylene glycol, butanediol, hexanediol and glycerol.

36. A process for preparing polymers from a monomer component comprising a mixture of diallyl carbonates of a diol or a triol, suitable for the preparation of organic optical glass, said mixture having been prepared according to the process of claim 31, characterized in that the polymerization reaction is carried out in the presence of a radical initiator which is a member selected from the group consisting of peroxides and peroxycarbonates, the quantity of said radical initiator relative to the monomer concerned being in the range from 1%
to 12% on a weight basis, said polymerization reaction being carried out at a temperature of from 30°C to 120°C.